Up to 25 percent of people with diabetes will develop a foot ulceration at some point during their lifetimes.1 There are a number of component causes that interact to complete the causal pathway to foot ulceration. However, the most frequent component causes are peripheral neuropathy, deformity and trauma.2,3
Deformity leads to increased plantar pressures and when these are combined with sensory neuropathy, ulcer formation is likely. Therefore, one must consider foot deformities as a possible cause for all foot ulcers.
There have been many new, exciting advances in the treatment of diabetic foot ulcerations. However, it is the fundamentals of care that one must prioritize. The basic, fundamental aspects of care include infection control, debridement and offloading. It is also important to ensure adequate limb perfusion and determine if there is an ischemic component to the wound.
Proper offloading is an essential component in the overall care of patients with diabetes but this is often overlooked. Adequate offloading starts with recognition of underlying deformities and subsequent implementation of a pressure reduction plan. Adequate pressure reduction may occur extrinsically through casts or specialized boots, or intrinsically through surgery.4 The gold standard for non-surgical offloading of the foot is the total contact cast.5 When it comes to the non-infected, non-ischemic, plantar neuropathic foot ulcer, researchers have reported the effectiveness of total contact casting with healing rates ranging from 72 to 100 percent.6
However, a total contact cast does not correct the underlying fixed deformity and one study showed an 81 percent ulcer recurrence rate after two years.7 In situations in which there is a deformity that prevents the efficacy of short and long-term solutions, surgical intervention is warranted. Researchers have described various surgical procedures to assist in ulcer healing. These “curative”-type procedures are designed to augment healing and reduce the risk of ulcer recurrence.8
Limited ankle joint mobility, as one may see clinically as a tight Achilles-gastrocnemius-soleus complex, is a deforming force that physicians must consider as a causative factor in plantar forefoot ulcerations. During normal gait, 10 degrees of dorsiflexion of the foot is required. Less than this will increase plantar pressures in the forefoot and impede healing of the wound.
Weighing The Pros And Cons Of Percutaneous TAL And Gastrocnemius Recession
To alleviate the forefoot pressure, several authors have suggested percutaneous tendo-Achilles lengthening (TAL).9-12 Armstrong and co-workers confirmed that plantar pressures are reduced after percutaneous TAL.13
Lin and colleagues performed a percutaneous TAL on 15 patients with foot ulcers that were resistant to healing with conservative care. All but one ulcer healed and there was no ulcer recurrence after a mean 17.3-month follow-up.14
Mueller and colleagues conducted a randomized control trial of 64 patients, comparing the combined treatment of total contact cast and percutaneous TAL against a total contact cast alone.7 Healing rates were higher in the tendon lengthening group (100 versus 88 percent). However, the dramatic difference was in the recurrence rate. After two years, there was an 81 percent ulcer recurrence rate in the group treated with a total contact cast alone in comparison with 38 percent in those treated with a total contact cast and TAL.7
Unfortunately, one cannot control the amount of tendon lengthening with this procedure and over-lengthening can result in a calcaneal gait. In patients with an insensate heel, this can result in heel ulceration. This complication occurs in up to 10 percent of patients and often requires a partial calcanectomy and local muscle flaps.12 There is also a risk of tendon rupture with a percutaneous lengthening and this will result in heel ulceration if the surgeon does not address this. These complications may result in a difficult to heal ulceration and may lead to a high-level amputation if one does not manage this appropriately.
A gastrocnemius recession may be a safer alternative to a percutaneous TAL. One may be able to have better control of the amount of lengthening and the gastrocnemius recession preserves the plantarflexion muscle strength. However, a gastrocnemius recession carries a higher recurrence rate of late plantar forefoot reulceration.12 To avoid over-lengthening, we routinely perform a gastrocnemius recession to assist in the healing of plantar forefoot wounds.
In addition to addressing the equinus deformity, the podiatric surgeon must also address other biomechanical deformities that may be contributing to the ulceration. Failure to include these adjunctive procedures with a TAL may prevent healing or accelerate ulcer recurrence.12
What You Should Know About The Percutaneous Flexor Tenotomy
Common forefoot deformities that are known to increase pressures and are associated with skin breakdown include hammertoe, clawtoe and first metatarsophalangeal (MPJ) deformities (hallux limitus/rigidus).3 One may perform a simple digital arthroplasty to address the contracture deformity of a hammertoe and relieve pressure at the ulceration. Percutaneous flexor tenotomy is an option for the treatment of neuropathic toe ulcerations secondary to contracture deformity.
In a systematic review of electronic databases and all relevant sources, Roukis and Schade identified two studies that fit their inclusion criteria (which involved consecutively enrolled patients undergoing the same procedure and follow-up of at least 12 months’ duration).15 Both studies were retrospective case series and involved percutaneous flexor tenotomy of the hallux and/or lesser toes. All patients experienced healing with the incision and the index ulceration. Although the methodological quality of both studies was poor, the studies support the ability of a percutaneous flexor tenotomy of the hallux and lesser toes to heal neuropathic toe ulceration secondary to toe contracture in people with diabetes.15
Key Insights On First MPJ Arthroplasties
Limited joint mobility at the first MPJ increases pressure plantarly at the distal hallux during ambulation. This can lead to ulceration under the hallux. This is a clear indication for curative surgery to address the underlying deformity and thereby reduce the distal pressure and assist in wound healing.
Armstrong and colleagues compared the safety and efficacy of a first MPJ arthroplasty (Keller-type procedure) with non-surgical management for wounds at the plantar aspect of the hallux interphalangeal joint (IPJ).8 The surgery group healed significantly faster than patients in the non-surgical group. Care after healing was identical in both groups and the surgical group had fewer ulcer recurrences during the six-month follow-up.
There was a very high prevalence of postoperative infections in the surgical group but this was in comparison to the proportion of patients in the control group who required treatment for infection during the period of therapy. The results of this study suggest that a first MPJ arthroplasty is a safe and effective procedure in the treatment of non-infected, non-ischemic wounds beneath the hallux.8
What The Research Reveals About Metatarsal Head Resections
Neuropathic ulcerations under the metatarsal heads are a challenging problem and may lead to infection and amputation.16 Armstrong and co-workers evaluated the outcomes of an isolated fifth metatarsal head resection for ulcerations beneath the fifth metatarsal head and compared it to non-surgical care. The authors reported a faster healing rate and lower recurrence rate in the surgical group.17
Hamilton and colleagues proposed combining lesser metatarsal head resection with gastrocnemius recession and a peroneus longus to brevis tendon transfer in patients with chronic, neuropathic forefoot ulcerations.16 With all the ulcers being located beneath lesser metatarsal heads, the authors were able to preserve the first MPJ. The authors adjunctively addressed the equinus deformity with a gastrocnemius recession and alleviated pressure under the first metatarsal with the peroneus longus to brevis transfer. The authors retrospectively reviewed 10 patients who underwent the proposed surgery and all of the patients achieved ulcer healing with no ulcer recurrence at a mean 14.2 months of follow-up.
In a prospective cohort study involving 26 patients with chronic ulcerations under the first metatarsal head, Dayer and Assal performed a modified Jones extensor hallucis longus and a flexor hallucis longus transfer.18 If the first metatarsal was still plantarflexed, the surgeons performed a peroneus longus to brevis tendon transfer. The authors also addressed an equinus deformity with a gastrocnemius recession.
Twenty-three patients were available for follow-up and all but one achieved complete ulcer healing and no ulcer recurrence at a mean 39.6 months.18
Identifying and adequately offloading an underlying fixed deformity is essential for both healing an ulceration and preventing ulcer recurrence. Offloading with casts or specialized boots may be effective. However, there may be instances in which surgical intervention is required to augment healing and reduce the chance of ulcer recurrence. The results of the aforementioned studies suggest that certain “curative”-type procedures are safe and effective in the treatment of the neuropathic ulcerations.
Dr. Bevilacqua is an Associate Medical Director of the Amputation Prevention Center at Valley Presbyterian Hospital in Los Angeles. He is a Fellow of the American College of Foot and Ankle Surgeons.
Dr. Rogers is an Associate Medical Director of the Amputation Prevention Center at Valley Presbyterian Hospital in Los Angeles. He is a Fellow of the American College of Foot and Ankle Orthopaedics and Medicine.
Dr. Steinberg is an Assistant Professor in the Department of Plastic Surgery at the Georgetown University School of Medicine in Washington, D.C. Dr. Steinberg is a Fellow of the American College of Foot and Ankle Surgeons.
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